For the past several decades, the scaling of features in integrated circuits has been a driving force behind an ever-growing semiconductor industry. Scaling to smaller and smaller features enables increased densities of functional units on the limited real estate of semiconductor chips. For example, shrinking transistor size allows for the incorporation of an increased number of memory devices on a chip, lending to the fabrication of products with increased capacity. The drive for ever-more capacity, however, is not without issue. The necessity to optimize the performance of each device becomes increasingly significant.
On-die voltage regulation is designed to automatically maintain a constant voltage level for an associated semiconductor die. A voltage regulator may be a simple “feed-forward” design or may include negative feedback control loops. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.
Electronic components, such as inductors, may be implemented on substrates such as an integrated circuit die or a printed circuit board (PCB). Such implementations involve placing patterns of material (e.g., as conductive material) on one or more substrate layers. This placement may be through lithographic techniques. Inductors used for RF applications in complementary metal oxide semiconductor (CMOS) technology are typically air-core spiral inductors. Various drawbacks are associated with these inductors. For instance, air-core spiral inductors typically require a substantial amount of space (area) on a substrate (e.g., an IC die). Moreover, such inductors require a high-resistivity substrate.
Thus, significant improvements are still needed in the area of on-die inductors for voltage regulation.